Sander



Aug. 4, 1942. c. A. CAMPBELL SANDER Filed July 5, 1940 4 Sheets-Sheet l (Ittomegs I Aug. 4, 1942. c. A. CAMPBELL, 4v

SANDER Filed July 5, 1940 4 Shets-Sheet 2' NON-5ANDING POSITION.

Zinnentor B s2 81 83 g attorneys Aug. 4, 1942. c. A. CAMPBELL 2,291,874

' SANDER Filed July 5, 1940 4 Sheets-Sheet B 76 74 75 FORWARD SANDING 129 DRIVERS.

wig/111111111 L, VIII/III g QEVEQSESANDING DRIVERS.

76 75 MANUAL RESET posmou 74 AFTER. TIMING SANDRNG.

45 I 7 I Gttornegs A 1942- c. A. CAMPBELL 2,291,874

' SANDER Filed July 5, 1940 4 Sheets-Sheet 4 TIMINGSANDINGJNITIAL MANUAL ACTUATION OF TIMING SANDING BUTTON 385%.

Ihwentor Patented Aug. 4, 1942 2,291,874 SANDER,

Charles A. Campbe]l,.w N Y i to The New York Air Brake O ass gnor ration of New Jersey ompany, a corpo.

Application July 5, 1940, Serial No. 344,148

12 Claims.

This invention relates to track sanders and particularly to a controlling valve mechanism adapted to be operated manually, or automatically in response to some of a train brake system, to cause sanding.

In a prior Patent 2,035,533, March 31, 1936, I describe and claim a valve of this type capable of being manually operated, either to sand-atwill or for a definite time period, and capable of responding to the functioning of the brake system to sand for the same definite time period. This valve has since been improved by the incorporation of means manually operable to terminate timed sanding while this is in progress.

The patented valve was designed for use on Diesel electric streamliners and has been successful. For steam locomotive service it is desirable to provide selective sanding-at-will for both forward and reverse running, and desirable that manipulation approximate that characteristic of old style systems, because of deeply rooted habits of steam locomotive drivers.

The present invention meets the above conditions, retains allthe operative characteristics of the patented device, and reduces the cost of manufacture by permitting substitution of a slide valve for-the expensive acteristic of the earlier device,

A single rotary valve mechanism performs all the sanding-at-will functions and thereset function for timed sanding. This valve mechanism forms a distinct replaceable unit.

The timing valve and the manually actuated valve for putting it into action form another distinct unit. The timing set button which actuates the last named valve has a protected location remote from the sanding-at-will valve handle so that the risk of its unintentional actuation while sanding-at-will is virtually eliminated.

This subdivision into units is desirable. Timed sanding is used during brake applications and is active throughout the sander equipped portion of the train. In some trains all the cars are equipped with sanders. Such sanding systems are approaching standardization, but are of relatively recent origin.

Sanding-at-will is used in starting and in grade work, and is needed only on the propelling unit. Various sanders of this type are in use; To sand forward and reverse, various relay and selective arrangements are practicable and many are in use. Standardization is more difficult, in consequence. The rotary valve and seat are components which can readily be modified to meet particular conditions as lapped piston valve charbrake-applying function entailing any change in the timed sandin and their incorporation in a separate unitzf fz ifis opportunity to modify details of porting.

To bring out the above thought a system will be described in which forward sanding is caused by developing pressure on the motorelement of a pressure actuated switch, and reverse sanding.

is caused by venting a normal] y charged line controlling a pneumatic relay. The rotary valve is readily designed to meet these particular conditions, and others that might be im 0 In the drawings sed' Fig. 1 is a diagram showing the valv e of the present invention applied to a sanding system for a locomotive and tender having forward and reverse sandmg for the locomotive devices and forward sandmgalone on the tender. The tender sanding unit is typical of that on any trailing zriiltaand gJuId be repeated on successive cars of n. ence in Fig. 1 the tend trailing unit, er typmes any Fig. 2 is a diagram of the sanding control valve mechanism in running (non-sanding) position.

Fig. 3 is an elevation of the rotary valve handle 1n non-sanding position.

Figs. 4 and correspond respectively to the rotary valve portion of Fig. 2 and to Fig. 3 butshow the position for forward sanding of the drivers.

I F1gs. 6 and 7 are similar views showing the position for reverse sanding of drivers.

Figs. 8 and 9 are similar views showing the posltion for manually resetting the timing valve.

Figs. 10 and 11 correspond to Figs. 2 and 3 22131 shovcilrpositilons assumed by the piston actusan mg va ve when the timi pressed. I ng set button is Fig. 12 shows the positions assumed d I urmg the timed interval after releas buttone of the timing set Referring first to Fig l a general stat t of the sand trap control, avoidin deta' emen material, will be given. g 115 not here The forward driver sand traps appear at 2IF ing air from a corresponding sanding control relay. The forward driver sanding relay appears at 24F, the reverse driver sanding relay at 24R.

and'the tender sanding relay at 24T.

The relays 24F and 24T are identical with each other and relay 24R. difiers in that blanking to sanding-at-will without 55 plates 25 and 26 are substituted for the magnet valve unit and for the pneumatic local control valveused with the other two relays and hereinafter described. Relay 248 has a special type of pneumatic control.

So far as is material here, relay 241?. is in run-' ning (non-sanding) condition when pipe 21 is under pressure. As pipe 21 is vented, relay 24R delivers air from reservoirs 23 to its clean-out line 22R and sander line 23R and then to the latter alone. As pressure in line 21 is restored, the relay cuts of! the air from sander line 23R, delivers a short blast to clean-out line 22R and r then vents both lines.

The relays 24F and24T on the other hand are normally put into action by energization of magnet valves 29F or "T as the case may be and are put out of action by deenergization of these magnet valves. In going into and out of action they perform the same cycles above described as to relay 24R.

The pneumatic valves 3IF and MT and timing reservoirs 32F and 32'! are controlled through connections 33F and 33T from local brake control valves "(not shown for operating the sanding relays locally and independently of magnet valves 29F or "T under certain conditions of braking not here material. The reservoirs 28 are charged from a brake system reservoir (not shown) through a valve 34 and the reservoir 35 for relay T is similarly charged through a valve 35. The function of valves 34 and 36 is to prevent the sanding system from depleting braking air under certain conditions not here material.

The relays and certain details of their relation to the brake system and electric circuits form the subject of a prior application Ser. No. 339,387, filed June 7, 1940, and the sand traps and controls are the-subject .of applications Ser. Nos. 314,172 and 314,173, flied January 16, 1940. These three applications resulted respectively in Patents Nos. 2,243,244, 2,243,242 and 2,243,243, each of which issued May 2'7, 1941. Hence claims to these details are not presented i'n-the present application. Further, since the present case has to do solely with control of such relays, only the ultimate functions of the relays need be stated. In short, the purpose of Fig. 1 is to ofler a typical system, for which no novelty is here claimed, as a basis for disclosing the various operative functions 2-12.

In Fig. 1, battery 31 supplies current through normally closed switch 39 to the sanding circuit which has two parts,'a locomotive circuit which controls the winding 29F, a train' circuit which includes the tender relay winding 29T, and would also include similar windings on carsin cases where the train is made up of cars having electrically controlled sanders. To limit sanding-at-will to the drivers, without so limiting timed sanding, use is'-.inade of an interlocking switch according to the principles described and claimed inmy allowed application Ser. No.- 266,819, flied April 8, 1939, which issued as Patent No. 2,222,604 .on November 26, 1940.

Wire 39 is a common return line connected with one terminal of battery 31 and one terminal of magnet valve 291', one terminal of magnet valve 291 and one terminal of each of similar magnet valves (if ,used) on cars in the train. The connector 4| represents a connection to Sueceeding car' circuits which may be used accordin: to the disclosure of Patent No. 2,222,604.

of the sander control valve o'f Figs.

tion similar to of the tender unit 24T and connected parts, without change of function, detailed illustration is not considered necessary.

The wire 42 leads from the other terminal of the battery 31 through a normally open sanding switch 43 which is closed when pressure is admitted to the diaphragm motor 44 by way of the pipe 45. From the switch 43 the wire 49 leads to a second terminal of magnet valve 291. Thus whenever sanding switch 43 is closed, the forward sanders for the drivers will operate. A branch wire 41 leads from the wire 49 through a normally closed switch 43 to the wire 49. The switch 48 is opened when pressure is admitted to the diaphragm motor 5| through the pipe 52. Switch 49 is the so-called interlocking switch. The wire 49 leads to the second terminal of the magnet valve "T and also to the connector 4| by which the wires 49 and 39 may be connected to a train circuit extending throughout the train.'

as is well understood in the art. Thus, if pressure is admitted to the motor 44 and not to the motor 5|, all the electromagnetic valves 29F, 29T are operative in unison so that sanding occurs on the locomotive, on the tender and, if the cars are equipped with electrically controlled sanders, also on the cars. On the other hand, if both the motors 44 and 5| are operated, sanding will occur on the locomotive only. No claim is made to this principle because it is part of the claimed subject matter of the prior application last above identified.

The numeral 59 indicates a pipe to which air is delivered during a brake application, usually only during an emergency brake application. from some part of the brake system, according to principles well understood in the art. This pipe leads to an impulse valve shown in section at 53. Pipe 59 delivers to a chamber 54 beneath the diaphragm 55, which is urged by a spring 56 against a valve seat 51, the latter controlling to build up pressure in the chamber 52 so that shortly the diaphragm 55 will again seat on the valve seat 51 and terminateflow to the impulse pipe 58. When this flow is terminated the choke 59 will slowly vent the pipe 58. It follows that when a brake application, and particularly an emergency brake application occurs, pressure will be developed in the impulse pipe 53 .and then dissipated. Such impulse valves are known in the art and one is described, for example, in Patent No. 2,243,244, wherei't performs a tunethat performed in the device here disclosed.

The apparatus so far described involves merely one of several highly refined sanding systems appllcable toilocomotive and tender, or to locomotive, tender and train, and with whichthe sander control valve now about to be described maybe Since this involves merely repeated duplication used. -While thesystem as such is not a part of the present invention, it appears necessary to develop its basic functions in order that all the operativechara'cteristics of the sanding control valve'may be fully understood.

Reference shouldnow be made to Figs; 2 to 12 inclusive, particularly to Figs. '2 and 3. Y

-The sander control valve mechanism is mounted on a bracket 88 to which all pipe connections are made and comprises a body 84,- in which the piston actuated timed sanding valve and the timing set button mechanism are mounted, and

the housing 65 removably mounted on the housing 64 and in which the rotary valve for controlling sanding-at-will and reset functions is mounted.

To the bracket 63 there are. a number of pipe connections leading to ports in the bracket and in housings 64 and 65. Certain of these pipes have been and others will be identified by reference numerals on Fig. 1 and where this is the case the communicating ports in the parts 63, 84 and 85 will be given reference numerals corresponding to those applied to the pipes, of which the ports are simply continuations. In this way the flows can be traced more easily and the reference numerals can be simplified.

There is a passage 21 forming a continuation of the pipe 21 which controls reverse sanding relay 24. There is an exhaust passage 66 leading to atmosphere. There is a sander switch passage 45 forming a continuation of the sander switch pipe 45 and from this a branch passage leads to atmosphere by way of the flow restricting choke 81. There is a timing chamber passage 58 leading by way of a similarly numbered pipe to the timing chamber 89 of Fig. 1. There is an air supply port II connected by a similarly numbered Pipe with the reservoirs 28 of Fig. 1. There is an interlocking, switch passage 52 forming a continuation of the pipe 52 of Fig. 1 and there is an impulse passage 58 forming a continuation of the impulse pipe 58 in Fig. 1. The connections just described relate the sander control valve mechanism to the sanding system previously described. 1

Enclosed by a cap 13 mounted on the housing 85 is a chamber 14 in which is mounted the rotary valve 15, which is the valve used to perform all sanding-at-will functions and the timed sanding reset function. The valve is operated by a key 16 on the stem 11 which is shiftable by a handle 18. The handle 18 has an impositive roller latch 19 which retains the handle in its normal or non-sanding position shown in Fig. 3. From this position it may be swung forward, i. e., clockwise from the position shown in Fig. 3 to the forward sanding position shown in Fig. 5. In the last-named position an arm 8| formed integrally with the handle 18 engages the end of the spring plunger 82. Further clockwise movement is resisted by the spring plunger 82 and such further movement carries the handle 18 to manual reset position, Fig. 9. If the handle is released in the position of Fig.9, the plunger 82 will return the handle to forward sanding position, Fig. 5.

Motion of the handle 18 rearward, i. e., counterclo'ckwise from the position of Fig. 3, is opposed by a second spring plunger 83. If this spring'plunger is overpowered, the handle moves to reverse sanding position, Fig. 7, and from this position the spring plunger 83 will restore the handle to non-sanding position, Fig. 3, if the handle is released. Thus the handle, and consequently the rotary valve, are impositively retained in non-sanding position by the latch 19. They can be moved to forward sanding position, Fig. 5, and left there, which is a desirable characteristic because in grade work continuous sanding of the drivers is occasionally desirable. If the handle is moved to reverse sanding position,

it is automatically returned to non-sanding position, and if it is moved to reset position, it is automatically returned to forward sandingposition. I

The spring return of the valve from reset position is considered important because it would be confusing if the handle were left in that poworks in the cyinder 81.

sition. There is no occasion for it to remain in reset position since the reset function takes place' The porting of the seat of the rotary valve I5 I can now be explained. The reverse sanding passage 21 leads to a port in the seat-of the valve, as clearly shown in the drawings. So also does the exhaust passage 66 and the sander switch passage 45. The air reservoir passage ll leads to the chamber 14 and in certain positions of the valve 15 supplies air to the passages in the seat by way of ports in the valve.

In Figs. 2, 4, 6, 8 and 10 the porting of the valve and seat is diagrammatic to the extent that the ports are drawn as if they lay'in a single plane according to a convention commonly used in the air brake and related arts. In commercial practice more compact arrangements can be had by other port locations but these are conventional 'matters of design.

There are two other ports in the seat of the valve 15, one communicating with the bridging passage 84 hereinafter described and the other communicating with a reset passage 85 hereinafter described. Since these two ports are related to the timed sanding slide valve and piston in housing 64, further description must be suspended until that valve has been described.

In the housing 64 is a slide valve chamber 85 and a cylinder 81. The outer end of the cylinder is closed by cap 88 which is sealed by a gasket 89, the gasket extending inward far enough to offer a-seat to a flange on a piston 9| which The-piston moves full stroke between a normally non-sanding position, shown in Fig. 2, and a sandingposition, Fig. 10. It is biased toward normal position by a compression spring generally indicated at 92. A special spring assembly with retainer stem is shown, but this is simply a conventional arrangement facilitating mounting of the spring in the cap and assembly of the parts.

The piston 9! has a stem 93 which is guided by a ported spider 94 in a portion of the valve chamber 86. Between the spider 94 and the shoulder 95 on the stem 93 a slide valve 96 is confined, so that it partakes of all of the motions of piston 9!. This valve 96 is held to its seat 91 by a thrust pin 98 which seats at its upper end against the rubber-like element 99 which serves not only as a gasket between the housings 84 and 65, but also as a flexible diaphragm reacting downward on the stem 98. The portion which serves as .a diaphragm is subject on its upper side to air reservoir pressure communicated by passage H. The diaphragm is further loaded by a coil compression spring IOI. Thus whether the valve chamher 88 is or is not under pressure, the valve 88 is properly held to its seat 81.

The reset passage 88 previously described is-oi substantial flow capacity and leads to the space at the outer side 01 the piston 8|. The space to the left of the piston and within the valve cham-- lockingswitch passage s2, a port m in com munication with bridging passage, a restricted charging'port I22in communication with rash.

voir passage II, and a port I'28'in communica-' tion with sanding'switch passagev 88.

The slide valve 88 has sun-such charging port I28 and a cavity |28so arranged that in running position reservoir port I22 is connected in chargwhich time the slide valve chamber 88 and reservoir 88 are vented to atmosphere at a restricted rate by way of choke 81, with the result that. when the pressure falls suillciently, the spring 82 will restore the piston 8| and the valve 88 to the non-sanding or normal position of Fig. 2. It is thus that timed operation of the valve 88 is had.

The space to the right, that is on the outer side of the piston 8|, may be vented by the manual operation of the timed sanding set button I82 or by the admission oi pressure fluid to the impulse connection 88. Either of these actions may be momentary but each sets into action a train of events which continues until the piston 8| has completed its-outward and inward cycle oi motion either over the timing period or over some shorter period'terminated. by manipulation of handle I8 to the reset position of Fig. 9.

The means for putting the timing sanding mechanism into action will now be described. Reier particularly to Figs. 2, 10 and 12.

ing relation with the slide. valve chamber, the sander switch port I23 and exhaust port I I8 are blanked and interlocking switch passa e 82 and bridging passage" are connected with each other by. the connection-of'polfts'in and I2I. Port I88'is eup0sed-;I; iy the outer end 01 the slide valve 88,

However, in timed sanding position (Fig. 10)

sander'switchport l28isexposed; ports |2I and I22 are blanked;.while ports 8 and I88 are connected to exhaust port I I8. Thus when piston 8| moves to itsoutermos't position, the space to its right isvented at arestricted rateto atmosphere (via port I88),- while slide valve chamber v 88 and'connectedtiming, chamber 88 are connected to sander-fs'witch passage 88, from which the bleed :ch'oke' 81 leads to atmosphere. Thus the piston stays outward until the pressure in slide valve chamber 88 falls low enough for spring 82 to return the piston. When this occurs ports ..-I22 and I28 start tocharg'e chamber 88 and res- A passage I88 leads from the space to the right I of piston 8| to the chamber I88 and to the restricted equalizing port I88 in the seat 81- for slide valve 88. Opening inward into chamber I88 are two opposed'poppet valves I88 and |8|., These valves are both urged closed by com-' pression spring I88. Valve I88 may be forced ervoir '88, and port|88 starts charging flow from the slide valve chamber to the space at the right of piston 8|.

To understand the operation of the rotary valve 18, it should be observed thatin the non-sanding position 01- piston 8| and valve sg'. bridging pas-- sage 88. is'simply a continuation oi the interlocking switch passage 5:.

from its seat by timing button I82 opening communicationto chamber I88 beneath ball check valve II-I. From the upper side of check valve III a passage II2 leads to the space within cap II8 on the outer side 01' diaphragm II8.

Diaphragm H8 is clamped at its periphery by cap H8 and at its center reacts through thrust disc II8 upon valve I8'I to open the same. Im-

pulse passage 88 leads to passage II2 through a check. valve II 8 and constantly open choke II].

The s'pace'to' the right of diaphragm II8, into which valve I81 discharges, is connected to exhaust passage 88.

Thus if a pressure impulse is delivered to pipe and passage 88 by impulse valve 88 as the result oi a brake application (usually an emergency application) diaphragm I I8 is forced inward, opening valve I81, which vents the space to the right of piston 8I1to atmosphere. The piston 8|v and slide valve 88 assume the positionsoiFigrlo.

Similarly, if set button I82 ispressed'in, valve I I I I88 opens and air from the space to the right-o! piston 8| flows through valve I II and passagel I2 to the space to the left of diaphragm I I8, 'iorcing this in (see Fig. 10). The check valve II8 closes and the choke III delays dissipation of pressure .magnet valve 281" will be energized.

I Non-sanding possum-Fig. 2. Piston 8| is inward. Through port. I28 in valve I8 subjects passage 21 to pressure. Hence relay 28R is inert.

' Passage 88 is blanked by valve 18 and vented at 81. 'Hence sanding switch 88 is open. Passage 88 is vented by cavity I21. Hence interlocking switch ,88' is closed'so that it piston 8| moves out. both magnet valve circuits will be energized. Reset passage 88 is blanked.

Forward sanding-at-wilL-Drivers only. Fig.4. Port I28 puts passages 2'Iand 88 under pressure. Hence relay 28B. is inert and sanding switch 88 is closed.v Passage 88 is put under pressure by port I28. Hence interlocking switch 88 is opened .andsanding is confined to drivers since only Reset port "is blanked] v ,Reverae sandinmst-wiZZF-Drlvers only. Fig. 6.

' PortI8I vents passages 21 and 88; Hence relay 28R'is active, but it controls onlyidriver reverse Interlock 'switchiremains' so that n depression of set g g I button. Isa-mummy of air impulse to' pipe 88 as the resultvoian emergency application should-occur while the valve I8 is inthe os tionrortmg. scis, interlockhig on the diaphragm so that release of the set buttion of Fig.- 12.

Thus the piston 8| moves out re'sponse'toa to port I88, an exhaust port M8 connected with ton I82 leaves the parts temporarily in the posiswitchwill'be closed. If it occurs with valve II in the position 01' Fig.4, theinterlocking switch 88 willbe initially open but only until the shift of slide valve-881w the position of Fig.- 18 causes itt'o close.) In-"this latter position air'ircm the normally charged .timing reservoir 88 holds sanding switch '88 c losed until the pressure is dissipatedbyflow. through choke 81. Then piston 8| will automatically reset, recharging reservoir 88.

Reset during timed sandina.--Fig. 8. In this position port I32 vents the sanding switch passage 45 to end sanding byopening the switch 43. Port I38 charges passage 21 to hold relay 24R inactive and charges reset passage to force piston 9| inward, where it will remain. Observe that ifthe engineer is sanding in the position of Figs. 4 and 5, when an emergency brake application occurs, he cannot terminate sanding by shifting to running position of Fig. 2, for how through ports I28 and 45 will have held the charge in timing reservoir 69, and sanding will continue for the set time after he shifts to the position of Fig. 2. He should first shift to reset position, Fig. 8, and then to running position, Fig.

2. This amounts to saying that if timed sanding starts it will run its course unless reset position is used to terminate it sooner.

General considerationa-It will be observed that the switch 43 is an activator capable of putting all the forward sanding units into operation, and that the switch 48 is an inhibitor which prevents the operation of the units other than the driver units. Because the invention is broader than-any specific apparatus for putting it into efiect, these terms will be used generically in certain of the claims.

The important factor in the operation of the which it causes sanding independently of the pneumatically actuated valve, and a reset position in which it serves to reset the pneumatically actuated sanding control valve if then active and without regard to the termination of said time period.

2. The combination of a pneumatically actuated sanding control valve; means for putting said valve into action; timing means rendered active by the initial operation of said valve to maintain it active for a definite time period; and a manually actuated independent sanding control valve'having a running position, a forward sandingposition and a reverse sanding position on opposite sides of running position in each of which it causes sanding independently of the pneumatically actuated valve, and a reset position in which it serves to reset the pneumati-' cally actuated sanding control valve if then active and without regard to the termination of said time period; and two yielding stops, one resisting motion of the independent sanding control valve from running to reverse sanding I position and the other resisting its motion from device is that the timed sanding valve is the pri- I mary control. It operates all forward sanders and does so even though the manual sanding valve be set to operate the driver sanders and inhibit theoperation of other sanders. Thus if the engineer is sanding forward or reverse on the locomotive, a condition which would normally inhibit sanding throughout the train, and if at that time an emergency application caused the timed sanding valve to respond, the timed sanding valve would cut the'manual control valve out of control of the inhibitor and terminate the action of the inhibitor so that sanding would immediately occur throughout the train. The only thing the engineer can do when these circum-' stancesarise is to operate the manual sanding valve to reset position. If he does, he can terminate all sanding, but he has only the option of permitting sanding to continue throughout the train or to suspend it completely. This is an important point because the engineer should be protected against accidental interference with sanding caused by an emergency application. The safeguard is accorded by the relationship of the ports H8, 9,. I25 and I25 (see Figs. 2

and 10).

As explained, automatic sanding systems for trains are of relatively recent origin and are tending to become standardized. Driver sanding units have long been in use and have assumed various forms, only one of which isillustrated in the present application. The rotary valve I5 and its seat can be variously ported to meet the requirements of particular sanding systems and except as specifically recited in the claims the details of porting are intended to be illustrative and not limiting.

I claim:

1. The combination of a pneumatically actuated sanding control valve; means for putting said valve into action; timing means rendered active by the initial operation of said valve to maintain it active for a definite time period; a manually actuated independent sanding control valve having a running position, a forward sanding position and a reverse sanding position on opposite sides of running position in each of forward sanding position to reset position, said valve moving without resistance by said stops between running and forward sanding positions.

3. In a sanding system for a vehicle or train of vehicles having driving wheels and free running wheels, the combination of an electrically controlled sanding unit for sanding driving wheels in forward running; at least one electrically controlled sanding unit for sanding free running wheels in forward running; a pneumatically controlled sanding unit for sanding driving wheels in reverse running; a normally open pressure actuated sanding switch for energizing both said electrically controlled units; a normally closed pressure actuated interlock switch for disconnecting the second named electrically controlled unit to inhibit its actuation by said pressure actuated sanding switch; a primary sanding control valve having an inactive position in which both pressure actuated switches are vented; and a sanding position in which the pressure actuated sanding switch is subjected to pressure to cause it to close and the pressure actuated interlock switch is vented so that it remains closed; timing means rendered active by motion of the primary sanding control valve to sanding position and serving to maintain said valve in such position for a definite time period; means operable to shift said primary sanding control valve to sanding position; pressure operable reset means for restoring said primary sanding control valve to inactive position; and

' a manually operable sanding-at-will valve capable of functioning independently of said primary sanding control valve and having a forward sanding position in which it delivers pressure fluid to both said pressure actuated switches and maintains said pneumatically controlled sanding unit inactive, a neutral position, a reverse sanding position in which it renders said pneumatically controlled sanding unit alone active; and a reset position in which it vents said pressure actuated sanding switch to cause said switch to open and delivers pressure fluid to said pressure operated reset means.

4. In a sanding controller, the combination a primary sanding control valve comprising means forming a combined timing and valve chamber and associated cylinder, a piston reciprocable in said cylinder and subject on its opposite sides to pressures in said chamber and pressure in a reset chamber in the outer end of said cylinder, a spring biasing said piston toward said timing chamber, a valve seat in said timing chamber, a valve eoacting with said seat and connected with said piston to be shifted thereby between a running position to which the spring urges the piston and valve when pressures on the piston are equalized and a sanding position to which the piston moves when the reset 'chamher is vented, said valve and seat controlling ports as follows, a charging port to the timing chamber and a restricted equalizing port from the timing chamber to the reset chamber, both open in running and closed in sanding position, a sanding portleading from the timing chamber closed in running and open in sanding position, and bridging, interlocking and exhaust ports, the first two of which are connected and the third blanked in running position, whereas the first is blanked and the second and third connected in sanding position; means for venting said reset chamber to put said primary sanding control valve into action; and a manually operable secondary sanding control valve shiitable independently of said primary control valve and having asanding position in which it delivers air under pressure simultaneously to said sanding and brid in po son the piston are equalized and a sanding position to which the piston moves when the reset chamber is vented, said valve and seat controlling ports as follows, a charging port"to' the timing chamber and a restricted equalizing port from the timing chamber to the reset chamber, both open in running and closed in sanding position, a sanding port leading from the timing chamber closed in running and open in sanding position, and bridging, interlocking and exhaust ports, the first two of which are connected and the third blanked in running position, whereas the first is blanked and the second and third connected in sanding position; means for venting said reset chamber to put said primary sanding control valve into action, said means comprising a pressure operated vent valve, and a manually operable valve serving when actuated to deliver operating pressure fluid thereto; and a manually operable secondary sanding control valve operable independently of said primary sanding control valve and having a sanding position in which itdelivers air under pressure simultaneously to 5. In a sanding controller, the combination a primary sanding control valve comprising means forming -a combined timing and valve chamber and associated cylinder, a piston reeiproeable in said cylinder and subject on its opposite sides to pressures in said chamber and pressure in a reset chamber in the outer end of said cylinder, a spring biasing said piston toward said timing chamber, a valve seat in said timing chamber, a valve coacting with-said seat and connected 'with said piston to be shifted thereby between a running position to which the spring urges the piston and valve when pressures on the piston are equalized and a sanding position towhich the piston moves whenthe reset chamber is vented, 1

primary sanding control valve into action, said means comprising a pressure operated vent valve; and a manually operable secondary sanding control valve operable independently of said primary sanding control valve and having a sanding position in which, it delivers air under pressure simultaneously to said sanding and bridging ports.

,6. In a sanding controller, the combination of a primary sanding control valve comprising means forming a combined timing and valve chamber and associated cylinder, a piston reciprocable in said cylinder and subject on its opposite sides to pressures in said chamber and pressure in a reset chamber in the outer end of said cylinder,;a spring biasing said piston towardsaid timing chamber, a valve seat in said timing chamber, a valve coacting with said seat and connected with said piston to be shifted thereby between a running position to which the said sandin d bridging ports.

'7. The combination of a pneumatically actuated' sanding control valve; means for putting said valve into action; timing means rendered active by the initial operation 01' said valve to maintain it active for a definite time period; a manually actuated independent sanding control valve having a running position, a forward sanding position and a reverse sanding position on opposite sides of rimning position in each of which it causes sanding independently of .the pneumatically actuated-sanding control valve, and a reset position in which it serves to reset the pneumatically actuated sanding control valve if then active and without regard to the termination or said time period; and yielding means serving to move the manually actuated valve irom said reset position.

8. In a sanding system for a vehicle or train of vehicles having driving wheels and free running wheels, the combination oi at least one sanding unit for driving wheels and at least one sanding unit for tree running wheels; a pneumatically actuated'sandlng control valve arranged to operate all said sanding units; automatic means ior putting said sanding control'valve into action;

timing means rendered active upon operation of which it operates the sanding unit for the driving wheels and adistinct reset position in which it serves to reset the pneumatically actuated valve it then active,'without regard to the ter-.

mination of said time period.

9. In a sanding system for a vehicle or train of vehicles having driving wheels and free running wheels, the combination of at least one sanding unit for driving wheels and at least one sanding unit ioriree running wheels; s pneumatically actuated sanding control valve arranged to operate all said sanding units; timing means rendered active upon operation oi said sanding control valve to maintain it in action for a definite time period; automatic means for putting said sanding control valve into' action; manually operable means ior putting said sanding control valve sprin8 urges the piston and valve when pressures into action; and an independent manually oper.

able control valve connected to actuate me sanding unit for the driving wheels and also connected with said pneumatically actuated sanding control valve, said independent valve having a distinct reset position in which it serves to reset the pneumatically actuated valve if then active, without regard to the termination of said timing period.

10. In a sanding system for a vehicle or train of vehicles having driving wheels and free running wheels, the combination of at least one sanding unit for driving wheels and at least one sanding unit for free running wheels; pneumatically operable activating means for said sanding units comprising two pressure operated devices so arranged that supply of pressure fluid to both or only one thereof respectively causes operation of the sanders for all wheels or of the sanders for the driving wheels only; a pneumatically actuated sanding control valve connected to deliver pressure fluid to said activating means to operate the sanders for all wheels; timing means rendered active upon operation of said sanding control valve to maintain it in action for a definite time period; means for putting said sanding control valve into action; and an independent manually operable control valve arranged to deliver pressure fluid to said activating means to cause operation of the sander for the driving wheels only, the parts being so arranged that when both the pneumatically and the manually actuated sanding control valves are in sanding position the sanders for all wheels will be operated.

11. In a sanding system for a vehicle or train of vehicles having driving wheels and free running wheels, the combination of at least one sanding unit for driving wheels and at least one sanding unit for free running wheels; a pilot unit comprising a normally inert activator and an inhibitor so arranged that when the activator is inert all sanders are inactive, when the activator is active and the inhibitor inactive all sanders are operated, and when both activator and inhibitor are active the sanders for the driving wheels alone are operated; a primary controller connected with the pilot unit and operable to render the activator alone active; automatic means for putting said primary controller into action; a manually operable secondary controller connected with the pilot unit and operable to render both said activator and inhibitor simultaneously active; and intercepting means effective in the sanding position of theprimary controller to render the inhibiting means inert irrespective of the action of the secondary controller.

12. In a sanding system for a vehicle or train of vehicles having driving wheels and free running wheels, the combination of two independent;

sanding units; a pilot unit comprising a normally inert activator and a related inhibitor so arranged that when the activator is inert both sanders are inactive, when the activator is active and the inhibitor inactive, both sanders are active, and when both activator and inhibitor are active, one only of said two sanding units is ac tive; a primary controller connected with the pilot unit and operable to render the activator alone active; a secondary controller connected withthe pilot unit and operable to render both said activator and inhibitor simultaneously active: and intercepting means efiective in the sanding position of the primary controller to render said inhibiting means inert irrespective of the position of the secondary controller.

CHARLES A. CAMPBELL. 

